I also thought the same thing, until I saw the video. In the video you can clearly see that the wire does not stick to the former after he does the loop but it has a wider diameter.
In the end, it’s just a test with a piece of copper wire. I also have an N1201SA analyzer and callipers and I could try to fine tune the antenna.
I’ll also try your ⌀15 mm version as soon as possible (the wire with the loops is ready, I’m only waiting for the N-type connectors to arrive)